We start with an overview of relational databases whilst examining the training database. We will get comfortable with the tool we use during the training to write the queries (the training course typically uses Microsoft SQL Server and SSMS).

This session practices writing queries that select data from one table. We learn how to specify the columns we need and how to sort the data. We then focus on the WHERE clause to limit the data returned.

The key topics trained are:

• The syntax of the SELECT statement
• Using the Distinct keyword
• Order by
• Examples of WHERE criteria including wildcards, comparison operators and
  BETWEEN, LIKE and IN

There are a number of different ways that data from different tables can be queried using JOINs. We look at how and when to use the various JOIN commands.

The key topics trained include:

• Joining multiple tables in the FROM clause
• Different join types including INNER and OUTER joins and SELF joins

This session is an introduction to including mathematical calculations in your queries, for example how to multiply a quantity by a price, or how to calculate how old someone is. We also look at some of the useful date functions and how to use the functions to change the format of data.

The key topics include:

• Performing mathematical calculations
• The types of functions available in SQL
• Date functions including GetDate( ), DateADD( ), DateDIFF( )
• Conversion functions and their uses
• Column aliases

SQL offers a number of ways to consolidate and aggregate the output of your queries. We begin by learning how to calculate the SUM, COUNT AVERAGE, MIN and MAX across the whole dataset and then look at how to write GROUP BY queries and limit these with the HAVING clause.

The key topics trained include:

• How to write aggregate queries
• COUNT vs Count(*)
• GROUP BY
• HAVING